1. Pipe A can fill a tank in 6 hours. On account of a crack at the bottom of the tank through which water leaks, it takes an hour more for the tank to overflow. How long will the crack take to empty a full tank when pipe A is kept shut?

2. Pipe A that can fill a tank in 40 minutes and pipe B that can fill a tank in 20 minutes are opened when the tank is empty. Pipe B is shut 16 minutes before the tank overflows. How long did it take for the tank to overflow?

3. Pipe A can fill a tank in 36 minutes. Pipe B can fill the same tank in 72 minutes. There is a drain pipe, pipe C, at the bottom of the tank. A man opens pipe A and pipe B when the tank is empty and returns back to shut them when the tank should overflow. However, he finds that he had kept pipe C also open and shuts it immediately. The tank overflows in the next 6 minutes. How long will pipe C take to drain the tank, if pipes A and B are kept shut?

4. A tank is fitted with 22 pipes. Some of these are fill pipes that fill the tank and others waste pipes that drain the tank. If each fill pipe can fill the tank in 24 hours and each drain pipe can drain the tank in 16 hours, and if all the pipes are kept open simultaneously when the tank is empty, the tank overflows in 12 hours. How many of these are waste pipes?

5. Adrain completes 60% of a task in 72 days. He realizes that to meet his deadline, he needs additional help and gets Allen who is thrice as efficient as Adrain to help him. They complete the task with four days to spare. What was the deadline for the project from the day Adrain started work on it?

6. Working together A and B can complete a task in 18 days. If A worked alone, completed the first half of the task and then B took over from A, the task will be completed in 48 days. If A is more efficient than B, how long will A alone take to complete the task?

7. Working alone, Shiv will take 27 more hours to complete a task than if he worked with George to complete the task. Working alone, George will take 3 more hours to complete the task than if he worked with Shiv. How long will George take to complete the task, if he worked alone?

8. 5 men and 7 women can complete a task in 12 days. However, if 11 men and 9 women worked on the same task, the work will be completed only in 8 days. How long will a man and woman take to complete the task?